

//另一棵树的子树(力扣572)
class TreeNode {
      int val;
      TreeNode left;
      TreeNode right;
      TreeNode() {}
      TreeNode(int val) { this.val = val; }
      TreeNode(int val, TreeNode left, TreeNode right) {
          this.val = val;
          this.left = left;
          this.right = right;
     }
 }

class Solution {
    public boolean isSubtree(TreeNode root, TreeNode subRoot) {
        if(root==null){
            return false;
        }
        if(isSameTree(root,subRoot)){
            return true;
        }
        //注意是isSubtree不是isSameTree
        if(isSubtree(root.left,subRoot)){
            return true;
        }
        if(isSubtree(root.right,subRoot)){
            return true;
        }
        return false;
    }
    //判断是否相同
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if((p==null&&q!=null)||(p!=null&&q==null)){
            return false;
        }
        if(p==null&&q==null){
            return true;
        }
        if(p.val!=q.val){
            return false;
        }
        return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);
    }
}